Quote: Seems scrub would not be very important with a roller tip as it would be with a sliding type rocker tip, within reason of course.
Actually I think it would be the opposite. With a roller rocker the roller is round (obviously) and the pivot is fixed so you will definitely have scrub.
On the other hand a sliding type rocker could have its tip ground in an eccentric so that although there is still the friction, the contact point could be maintained at the very center of the valve tip. Never seen one like it but definitely a possibility!
